|Moss-Covered Eldhraun Lava Field and Fossil Sea Cliffs of the South Coast|
Young geologically, the island is elevated over 3,000 meters above the seafloor, while the nearly pole to pole, submarine mid-ocean plate boundary zigs and zags across Iceland on land in a shifting complex of interconnecting fracture zones, volcanic belts and faults.
|Outlet Glaciers Skaftafellsjökull and Svínafellsjökull across Skeiðarársandur|
The fact that Iceland lies at the juncture of two large seafloor physiographic structures - the interplate spreading center of the Mid-Atlantic Ridge and the Greenland-Iceland-Faroe Ridge - has not gone unnoticed by genetic theorists.
The commonly held view is that asthenospheric flow in the upper mantle beneath the plate boundary interacts and mixes with a powerful, deep-seated mantle plume. Less differential density promoted buoyancy that led to dynamic uplift of the Iceland plateau and exceedingly high volcanic productivity. A second perspective, one that is rapidly gaining ground, is plumeless, relies on shallow mantle processes and is consistent with Plate Tectonic theory.
|Outlet Glacier Skaftafellsjökull and Proglacial Lake|
Regardless of Iceland's genetic provenance, its unique landscape is a culmination of the opposing forces of construction via volcanism and sedimentation and destruction via wind, wave, water and glacial erosion. Working in concert, they have established Iceland as one of the most geologically active and dynamic places on Earth.
It's one of the few places where the intimate architecture of a mid-ocean ridge and its processes can be viewed on land. It serves as a modern analogue that demonstrates how the earliest landmasses on our planet likely formed. Whether they realize it or not, it's geology that brings everyone to this incredible place.
|Hexagonal Columnar-Jointing in Basalt at Hálsanefshellir Sea Cave|
ABOUT THIS POST
Herein, relevant definitions are italicized and important names are in boldface, when first mentioned. Global coordinates of various locations are provided. Unless otherwise stated, all photos were taken by my daughter and me.
Everyone's Icelandic geo-experience begins with their descent over the tip of Reykjanes, a peninsula that juts out to the southwest 50 to 60 km from the mainland. Peering out of the plane's tiny window or on the short drive to the capital at Reykjavik, the universal comment is that Iceland "looks like the moon" - drab, treeless, rough, monotonous and uninteresting. Of course, geologists know otherwise, and for them, it's when the excitement really begins.
It's there that the Reykjanes Ridge, the submarine extension of the Mid-Atlantic Ridge in the North Atlantic, comes ashore at Reykjanestá, the peninsula's southwest corner. On land, the ridge bends to the northeast and continues across the peninsula as the Reykjanes Volcanic Belt that separates the diverging North American and Eurasian plates.
The Reykjanes Volcanic Zone consists of four volcanic systems arranged en echelon (obliquely parallel) that endow the landscape with a myriad of tectonic and volcanic features. It's the reason Reykjanes is a geological paradise and world-class UNESCO Global GeoPark with 55 listed sites. Even the very tip of the peninsula at Reykjanestá is loaded with geologic features (below), all a consequence of the Reykjanes Ridge coming ashore.
It's a region of NE-trending fault zones, fissures and crater rows, Yngri Stampar lava flows, a main graben (open tensional fissure and on-land continuation of the Reykjanes Ridge), sea cliffs with pillow basalts and feeder dikes, lighthouse Reykjanesviti atop hyaloclastite mountain Bæjarfell (vertical white structure), a phreatomagmatic crater from the year 1226 (lower right), the Skálafell lava shield (center), the Gunnuhver geothermal (white plume) and adjacent Reykjanesvirkjun electrical power plant with its discharge reservoir (luminescent blue lake). Notice the sea stack of Karl off the coast. It's an eroded remnant of a crater cone related to the Stampar eruption.
|Reykjanestá facing West|
Go there: 63°48'40.85"N, 22°41'50.34"W
TWO CURIOUSLY DISCONTINUOUS RIDGES
Similar to the Reykjanes Ridge at the southwest, Kolbeinsey Ridge on the North Coast is a seafloor extension of the Mid-Atlantic Ridge that approaches Iceland from the depths of the Arctic Ocean. It continues obliquely southeast on land as the Tjörnes Fracture Zone. During Iceland's inception some 24 million years ago, both the Reykjanes and Kolbeinsey Ridges are thought to have been continuous on land but not on the modern landscape.
Instead, the subaerial (on land) ridges veer to the east and connect with a parallelogram-shaped complex of shifting volcanic zones, faults and tectonic plate boundaries. The explanation for the evolution of this structural anomaly over time is the subject of intense debate among tectono-theorists that look to the Earth's mantle for a solution.
SOME IMPORTANT STUFF ABOUT THE MID-ATLANTIC RIDGE
It's a mid-ocean ridge system of quasi-linear, continuous volcanic mountains with an axial rift valley. It lies along the N-S axis of the Atlantic seafloor between the continents of the Atlantic realm and marks the boundary between the slowly-separating North American-Eurasian plates in the north and South American-African in the south. It spans the globe some 16,000 km, nearly pole to pole, and is part of the world's longest mountain range.
As the tectonic plates drift apart (at ~2.5 cm/yr or 25 km/myr), upwelling magma from the mantle (precisely from where, what depth and whether a mantle plume or shallow process is involved) reaches the seafloor and generates new crust of the widening ocean basin. The constructive process gave birth to the Atlantic Ocean and, on a vastly smaller scale, the elevated basalt plateau of Iceland, the largest volcanic island in the world.
SURFACE MANIFESTATIONS OF EXTENSION
Rather than bridging two continents in a literal sense, it's a well-intended misnomer, a surface manifestation of the two massive plates diverging apart in Iceland. In reality, there are many swarms or zones of these faults on Reykjanes and elsewhere in Iceland, depending on where you look. At the Bridge, they're on-strike with the SW-NE trend of the Reykjanes Volcanic Belt, so that any one is good as another for "bridging continents", as least as far as the public is concerned.
"Velkomin á Ìslandi" the sign at Keflavik Airport proudly proclaimed on our drizzly, early morning walk across the tarmac. The terminal is an eclectic and hectic place with throngs of tours and tourists, students and earth scientists, Reykjavik nightlife seekers and all-night partygoers, and the trans-Atlantic stopover crowd coming and going.
In spite of the rain and dark sky, we were weather optimistic, since previous trips delivered abominable mixes of driving rain, wind, sleet and snow. Wisely, this time we chose summer. We didn't see the Aurora Borealis (aka Northern Lights), but we hiked at all hours of the evening in the midnight sun and felt no guilt about sleeping in (Tip: Bring a sleep mask).
|Keflavik Airport at the Tip of the Reykjanes Peninsula|
Go there: 63°59'39.37"N, 22°37'25.13"W
(Two Tips: Don't expect any grocery stores or gas stations in the remote interior, so plan accordingly. Fast-moving, bedrock-filtered water that emerges from lava interfaces is generally potable. Glacially-derived water is generally high in clays and undrinkable.)
|Backcountry Warning Sign in the Central Highlands|
Translation: Unbridged River Crossing (4x4 Only)
By our trip's end, our squeaky clean machine bore the battle scars of splashed river mud, wind-blown volcanic ash and four bent door hinges when gale-strength winds on our first day almost ripped them off the car when we stepped out downwind. This was most severe on the South Coast and was posted both online and the radio.
The climate of Iceland, although generally mild, is generally windy and wet. But in this region, faster warming of land than sea and nearby glacial influences can create extremely blustery days with broadcast warnings. (Tip: Open doors into the wind and check online)
|Julia in our Newly Rented, Clean Machine in a Hengill Geothermal Field|
Fully-fueled, well-stocked and still-early, we headed east toward Reykjavik on Route 41, the only road to the capital from the airport along the north shore. It travels over terrane-spanning, gently undulating, layered flows of basalt lava. In this region of Reykjanes, it traverses one of its youngest flows of Holocene age, the Arnarseturshaun flow ('hraun' means lava in Icelandic). Closer to the capital, we passed over two more that are only about 2,000 and 1,000 years old, Afstapahraun and Kapelluhraun.
Almost all of Iceland's bedrock consists of one flow after another that vary in age and built this incredible landscape. Appearing motionless and serene, the dynamic aspects of their eruption and emplacement are frozen in lava's solidified flow features that are evident to the discerning eye.
In 1965 and 1967, NASA sent astronauts from the Apollo program to Iceland to train for their lunar landing mission. In fact, they just had a reunion on the island in 2015. NASA plans on landing on the Moon and Mars by 2030 and have chosen, once again, Iceland as their preparation site for their journey due to the similarities of terrain. It's not just the repetitive, motionless and volcanic topography that affords Iceland its lunar-look, but its color. The explanation involves some igneous rock geo-chemistry.
SOME IMPORTANT GEO-CHEMISTRY (JUST A LITTLE)
Basaltic lava's somber appearance is due to its ubiquitous nature but also its dark color. It's a mafic igneous rocks (encircled below) - high in Mg and Fe oxide-containing minerals of pyroxene, olivine and amphibole. Lava flows in Iceland are either composed of basalt or rhyolite, although the presence of the former vastly exceeds the latter.
The extrusive lava flows (magma reaching the surface) may form at opposite ends of the igneous rock compositional spectrum. High emplacement temperatures for basalt and rhyolite (1000-1250°C. and 700-900°C., respectively) facilitate fluidity, although basalt's reduced silica content (aka silicon dioxide) confers far lower viscosity, which makes it 'runny' and justifies its terminology as a flood basalt.
As a result of its geochemistry, physical properties and downslope topography, basaltic lavas are typically voluminous and, although slow-moving, can travel considerable distances across the landscape, many tens of kilometers, spurned by a high rate of effusion from a volcanic fissure (linear vent) or monogenetic (single-event) volcano.
ICELAND'S INFAMOUS LUNAR-LOOK
Iceland's lunaresque appearance is also related to the profound absence of tall vegetation, which is related more to human presence than the harsh climate conditions, which everyone assumes. The truth is that Iceland was once heavily forested with beech, spruce, pine and alder in the warmer late Pliocene, before the onset of Pleistocene glaciation. Fossil documentation exists in bedrock sedimentary rocks of the Tertiary Formation, the country's oldest succession in West and East Iceland at 16 to 3 myr ago.
With succeeding Pleistocene glaciations, boreal (northern) flora became increasing species-poor. Even so, at the time of human settlement when the first Vikings arrived almost 1,150 years ago, forests covered 25 to 40% of the island. Today, forests cover only a tiny percentage of the landscape, a condition that Icelanders are intent on reversing, although challenging considering the extent of the project.
A CASE STUDY IN DESERTIFICATION
As in all agrarian societies, Iceland's early Viking settlers slashed and burned trees to create fields for growing hay and barley and grazing land for livestock, especially sheep. Grazing prevented downy birch regeneration, the dominant tree in Iceland, which further enhanced its decline along with volcanic eruptions of ash and catastrophic flooding.
Volcanic ash is rich in nutrients but makes fragile, poor soils that don't hold water and readily succumbs to the wind. In addition, birchwood was also an important early source of fuel for cooking and heating, construction material, animal fodder and charcoal for smelting iron implements and weapons, it being an Iron Age culture.
NATURAL ENERGY GALORE
Just before reaching Reykjavik, everyone passes three curiously long buildings lying immediately next to the highway. Easily overlooked by weary travelers heading to their hotel rooms in the capital, the structures are a subtle commentary on Iceland's abundant, renewable and inexpensive natural resources that provide almost 100% of its electricity and heat.
Iceland is a world leader in harnessing power that has attracted the aluminum industry. Energy-intensive electric furnaces that drive electrolysis are housed in the 900 meter-long, metal-framed buildings. Their smelters convert bauxite ore, delivered by ship from as far as Australia, to aluminum and require the abundant and cheap power that Iceland can provide.
It's ironic that Iceland's most popular geological attraction is completely man-made! Only 20 minutes from the airport, Bláa lónið is another example of the island's abundant and renewable natural resources. On every tourist's must-see list, the hot soak (37-39°C) and health spa is rich in dissolved minerals, especially silica and sulfur, and a curious strain of harmless and possibly beneficial blue-green algae.
It's highly unlikely that bathers and spa-goers are thinking about climate change and energy during their visit, yet the Blue Lagoon symbolizes Iceland's remarkable journey from oil independence to world leader in renewable energy. Created by accident but ingeniously repurposed, it's a wastewater discharge reservoir, a by-product of operation for the nearby Svartsengi Power Plant built in 1971 with high-temperature geothermal resources related to the presence of the Reykjanes Ridge.
(Two Tips: There are far less touristy, less expensive, geothermally-heated pools to be found in Iceland in the volcanic zones, even in Greater Reykjavik where there are four. Everyone that visits the Blue Lagoon and skips seeing the rest of Reykjanes is missing out on the peninsula's incredible geology.)
Our plan was to counterclockwise-circumnavigate the Ring Road or Þjóðvegur (vegur is 'road' in Icelandic) and a number of F-Roads ('F' for fjall or 'mountain'). The 1,332 km-long Ring Road (aka Route 1) is paved and well-maintained (only 33 km of it is gravel in the Golden Circle) and connects villages, towns and many attractions around the island.
F-Roads are gravel-surfaced and variably plowed or closed in winter. They lead to the desolate and glorious interior of the country. If remote canyons, glaciated volcanoes, moss-covered lava fields, stunning waterfalls, majestic rivers, blue mountain lakes, vast deserts of sand and virtually no crowds sound appealing, F-Roads are for you.
(Three Tips: Check websites for road closures and weathers conditions such as here. Many remote areas are out of cellular and GPS range. Fording rivers requires special skills and knowledge. Watch the tutorials on YouTube.)
They were initially used for statistics, court jurisdictions (crime is nearly non-existent in this safest country in the world), and governmental and national insurance purposes but are now used for tourism and geology of course!
Most first-time visitors use Reykjavik (purple arrow) as their travel-base and for scheduled tours, especially those that visit the Golden Circle (not-to-be missed) and site-packed South Coast regions. But, having your own vehicle is enormously liberating, far less expensive than using a guide, prevents having to back-track to the capital for the evening and most importantly, allows far greater exposure to Iceland's incredible geological features.
|Iceland's Eight Touring Regions and the Ring Road|
ECO-REGIONS ARE ALSO GEO-REGIONS
The eco-regions actually possess profound relationships with the geologic framework of Iceland, its genesis and evolution. For example, the 80 km-long Snæfellsnes peninsula in the northwest (green circle) is an example of outlier volcanism, separate but genetically related to the mainland complex maze of boundaries. As such, it's a flank or volcanic zone, one of two, the other being the Öræfi Volcanic Belt in the southeast.
Snæfellsnes is an ancient rift zone that gave birth to the peninsula and was active some 6 myr ago and still active today within the Snæfellsnes volcanic complex at the end of the peninsula. Öræfi is considered to be a nascent rift. They both bear formative relationships to the position of a theorized mantle plume that lies deep beneath Iceland.
The commonly held view is that Iceland's formation, elevated topographic stature above the seafloor, high volcanic productivity and ongoing evolution are due to the presence of the Iceland mantle plume. Its presence is a consequence of planetary cooling and is considered to be part of the convection mantle mechanism that drives plate tectonics on the Earth's surface.
Although numerous modifications exist, it's envisioned as a mushroom-shaped diapir of slowly ascending, unusually hot rock from the deep mantle or mantle-core boundary. At shallow depths, it begins to melt and produce magma (a grossly oversimplified explanation), and on the surface, produces a hotspot that is manifested as intense, vigorous and effusive volcanic and seismic activity. In the North Atlantic, it built the elevated basalt plateau of Iceland above the surrounding North Atlantic seafloor and is thus, sea floor on land.
|Schematic Impression of the Iceland Mantle Plume|
From the cover of Nature Magazine 1977
THE (POPULAR) PLUME MODEL
Although the plume is thought to be relatively stationary, the diverging MAR boundary of the North American and Eurasian plates migrates WNW relative to it, which makes the plume appear to move to the southeast. This activity may extend back some 130 myr, but in regard to seafloor spreading in the North Atlantic between Greenland and North Europe, it began ~55 or 60 myr ago, when the plume was somewhere beneath Greenland.
As spreading progressed, the Greenland-Iceland-Faroe Ridge formed as a volcanic land bridge between diverging Greenland and Eurasia, the fragmenting components of northern Pangaea. The GIFR is possibly part of the North Atlantic Large Igneous Province, a massive outpouring of igneous rock that preceded Pangaea's fragmentation and opening of the Atlantic Ocean. Volcanologically inactive, highly eroded remnants of the NAIP are distributed on the borders of the rifted continents of the Atlantic realm. The Palisades of the Hudson River in New Jersey and Giant's Causeway in Ireland are familiar examples.
Iceland remains as part of the GIFR and the only remaining, magmatically active portion of the NAIP formed of oceanic crust, while the rest forms a linear ridge on the seafloor. When the migrating plate boundary reached the plume some 24 myr ago, volcanic activity increased dramatically and formed elevated Iceland along the submerged GIFR, while its NW and SE regions became submerged. Thus, Iceland's oldest exposed rocks are only 14-16 myr.
GENETIC JUMPING RIFTS
As the spreading axis moves away from the plume, active new rifts form on land in an eastward direction to keep pace with it, that is, maintain relationships to the surface expression of the plume, while older rifts gradually become inactive. It explains why the Reykjanes and Kolbeinsey Ridges became discontinuous and reconnected to a central complex of shifting boundaries and rift zones in a gradual, transitional process called rift-jump.
SO, WHERE'S THE PLUME THESE DAYS?
Its head is thought to be located in the Earth's mantle below the northwestern part of ice cap Vatnajökull in southeast Iceland, while its tail, as mentioned, is somewhere beneath the Snæfellsnes Volcanic Belt of northwest Iceland. It's viewed as an extinct, rift-jumped precursor to the active West Volcanic Zone of the central complex. It helps to see all this on the "Principal Structural Elements of Iceland's Geology" diagram (down below).
A (PLUMELESS) PLATE MODEL
Don't buy the "Plume" model? Not everyone does. There's currently a potential paradigm shift in geology that's gaining ground (pun intended) that doesn't rely on "ad hoc assumptions", wrongly-interpreted data and exists "without first order observations" as does the Plume theory that is consistent with the theory of Plate Tectonics.
It expounds that Iceland's "anomalous volcanism" at its meltspot (and others globally) occurs "permissively" at areas of tectonic extension. At Iceland, it's where the Mid-Atlantic ridge crosses the Caledonian suture. The fault zone formed when Greenland, Scandinavia and Europe collided (tectonically unified) and the crust of the intervening Iapetus Ocean gradually closed and ultimately subducted into the mantle during the protracted formation of supercontinent Pangaea in the Paleozoic. See my Post I for more details.
As opposed to the Plumist model, the Platist model of Iceland's formation doesn't need a 'concocted' plume to explain its origin and is consistent with the almost universally accepted concept of Plate Tectonics. Take your pick.
ICELAND'S STRUCTURE (SIMPLIFIED)
Regardless of the theories, here's the structure of Iceland's plate boundary complex and what the components represent. Think of it this way. The submarine mid-ocean Atlantic Ridge is analogous to and roughly NS on-strike with Iceland's diverging volcanic belts on-land, while the EW on-land transform zones are comparable to seafloor fracture zones that are laterally offset to the MAR.
Transform fault zones are E-W trending plate boundaries with horizontal, strike-slip (side-to-side) motion that create high seismic (earthquake) and faulting activity. They're
conservative structures where lithosphere under shear is neither created nor destroyed. Most are concealed on the ocean floor, offset from mid-ocean ridges, but at Iceland they're on land and connect to spreading ridges where they accommodate eastward shift of the NVZ and EVZ:
• TFZ, Tjörnes Fracture Zone - the ocean-ridge discontinuity in North Iceland bridges the gap between the KR and NVZ and formed by shear stress between the NVZ and KR
• MIB, Mid-Icelandic Belt - bridges the gap between the WVZ and NVZ-EVZ triple junction
• SISZ, South Iceland Seismic Zone - earthquake region of strike-slip faults that bridges the gap between the WVZ and EVZ and takes up the transform motion (left lateral shear) between the Reykjanes Peninsula oblique rift and the EVZ
Divergent or spreading zones or belts are rift zones where lithosphere moves apart under tension. They're lineaments (large-scale linear features) that correspond to the submarine plate boundary across Iceland. The following segments comprise the Nevolcanic Zone, where most of the volcanic activity, magmatism and rifting occurs. It's also where, due to the elevation, most of the glaciation exists:
• RVB, Reykjanes Volcanic Belt - is the oblique on-land continuation of the Reykjanes Ridge through the Reykjanes Peninsula with left lateral shear motion and extension
• WVZ, West Volcanic Belt - is a continuation of the RVB with mostly extension and some volcanism (9%)
• EVZ, East Volcanic Belt - is a young "propagating" zone over the hotspot along with the NVZ. It appears to be taking over, a "rift in the making", from the receding WVZ, the main rift in South Iceland and where Iceland's four most (80%) active volcanic systems are located (Grımsvotn, Veidivotn, Hekla and Katla)
• NVZ, North Volcanic Zone - expression of the Mid-Atlantic Ridge in the north, see EVZ
The two flank or outlier volcanic belts of intraplate rifting, where younger rocks lie on older ones, indicating a significant time break are:
• SVB, Snæfellsnes Volcanic Belt - an ancient volcanic rift in the northwest that shifted to the WVZ thought to be related to the neck of the mantle plume and is superimposed on an extinct rift thought to be the precursor of the WZV.
• OVB, Öræfi Volcanic Belt - in the southeast on strike with the WVZ and EVZ and immediately to the east of the plume, which is thought to be beneath glacier Vatnajökull and possibly an embryonic rift and another future jump.
DESTINATION HENGILL AND HEKLA IN THE HIGHLANDS
Having left Reykjavik, we headed east on the Ring Road for our first two destinations - the volcanic systems of Hengill and Hekla in the southwestern highlands. They're located at opposite ends of the South Iceland Seismic Zone, where the transform zone contacts West and East Volcanic Zones, respectively.
On the west, the Hengill system formed at a triple plate junction. The ridge-ridge-transform (RRT) boundary is where the SISZ seismic boundary (dotted line) intersects two rift zones (black arrow) on the west - the West Volcanic Zone (WVZ) and the Reykjanes Volcanic Belt (RVB). The Hekla system is located at the intersection of the eastern end of the SISZ and EVZ, which forms a rift-transform (RT) plate junction.
The Hengill and Hekla systems are part of the Neovolcanic Zone of post-glacial Holocene-age (brown), where active volcanism is confined to about one-third of the island. It features nearly all known volcanic types: shield, stratovolcano, caldera, spatter, scoria and tuff cone, fissures, cone row, etc. They manifest most eruption types - Hawaiian, Strombolian, Vulcanian, Pelean and Plinian - but at Iceland, they're referred to as explosive, hydro-or phreatomagmatic, mixed, effusive, cataclysmic, etc.
HELLISHEIÐI IS HOT!
Upward wafting gases in the low hills around the Ring Road is the first indication of having entering the Hengill volcanic region. It's a 100 km-long, 3 to 16 km-wide, 100 sq km active system, having erupted in the last 2,000 years in the West Volcanic Zone. Hengill is the largest and furthest east of the previously mentioned four volcanic systems on the Reykjanes peninsula.
It's an area of significant tectonic, magmatic and high-temperature geothermal activity where two large geothermal power stations have been developed - Hellisheiði and Nesjavellir. Online at 2006, Hellisheiði is the largest of seven flash steam depressurization plants in Iceland (binary plants heat a secondary fluid that drives turbines) and second largest in the world. Heat sources are shallow magma intrusions fed by dike swarms, where erosion has exposed rocks formerly at a depth of 1-3 km.
Hellisheiði generates 303MW of electricity and 400MW of thermal energy via deep (~2.5 km) boreholes (over 30) that collects high-pressure hot water (>180°C) in proximity to a deeply buried magma chamber or associated reservoir. It's then directed to a low-pressure tank where it rapidly depressurizes and vaporizes and drives six steam turbines connected to a generator. Condensed water is returned to the subsurface via a well, while hot water is pipe-delivered above ground to Reykjavik for space heating.
|Hellisheiði's Maze of Transmission Pipes|
The largest geothermal power station in Iceland and the third largest in the world. About a third of electricity produced in Iceland is produced from geothermal power. The Ring Road is in the distance.
Across the Ring Road from the power station, telltale steam indicated another geothermal area of the Hengill system. Crossing over to investigate, we were the only ones there in contrast to Haukadalur Valley in the Golden Circle region, where caravans of buses vie for places to park and throngs of tourists shoot geyser selfies of Geysir and Strokkur and buy a few souvenirs (Tip: It's an important place to visit, but you'll have lots of company).
Although there were no geysers to be found, geothermal surface manifestations included ground that was warm to the touch with the smell of hydrogen sulfide gas in the air. Groundwater percolating through cracks and voids in the uppermost crust is heated (70 C. or more) and reaches the surface via vents in the form of fumeroles (venting gases of carbon and sulfur dioxide, hydrogen chloride and sulfide), steam vents (water vapor), hot springs and boiling mud pots.
The ground throughout the geothermal area has been thermally and chemically altered into hyaloclastites (volcaniclastic rocks formed by explosive water-magma fragmentation) and scoria (dark-red cindery basalt with acid-leached colors indicative of mineral content). Vegetation is limited to mosses and tolerant vascular plants due to severe chemical and physical factors.
Geothermal areas come in two flavors - high- and low-temperature. High's are located within or near active volcanic zones and indicate a shallow-crustal magma chamber. They're mostly on high ground with geologically young rocks that are permeable with a deep water table. Lows are found outside volcanic zones and are mainly hot or boiling springs. Their heat source is Iceland's abnormally hot crust related to tectonic activity and faults and fractures that are kept open and active for the flow of subterranean water.
HARNESSING GEOTHERMAL ENERGY
Adjacent to the geothermal hillside, a geodesic dome-like structure, one of scores that pepper the area, contains a wellhead. They contain a pressure regulator of a deep production well. On the top of the dome is a muffler that suppresses most of the deafening hiss of venting steam under extreme pressure. The flow of up to 300°C. water and steam is directed to an above-ground, zigzagging maze of elevated, insulated pipes.
|One of 30 Geodesic Domes and Production Geothermal Wells at Hellisheiði|
Slightly warm to the touch, the insulated long-distance, aluminum transmission pipes carry pressurized steam and geothermally-heated water from the wellhead to Hellisheiði's Power Plant turbines and generators back across the Ring Road.
"GATEWAY TO HELL"
At 1,491 m-high, our second destination in the southwest highlands was volcano Hekla, some 50 km east of Hellisheiði. It's Iceland's most famous, most notorious and most active volcano with 23 historical eruptions since 1104. Having last erupted in 2000, its construction is the result of repeated eruptions over 6 to 7,000 years from a 5.5 km-long fissure. It's possible that the fissure is a strike-slip fault, a side-by-side sliding earthquake fault that extends into the volcanic zone and has been reactivated by plate tectonics.
When it comes to dread and destruction, Hekla is in a class by itself. Carried by the wind, ash intermittently blanketed some two-thirds of the landscape, repeatedly darkening the sky, devastating agriculture and killing livestock that ingested or inhaled toxic fluorides that coat ash, binds calcium and interferes with bone and teeth maturation. During one documented extreme eruption in 1300, the density of airborne ash was that "no-one...could tell whether it was night or day."
THE NATURE OF HEKLA
Uniquely elongate, Hekla is a central volcano. Volcanic systems are the principal geological structure in Iceland with some 30 of them in the Neovolcanic Zone. Each consists of a central volcano, a linear volcanic fissure or both. With a typical lifetime of 0.5 to 1.5 million years, the latter may evolve into the former. Both are surface manifestations of a buried magma-holding reservoir within the crust. Hekla demonstrates a common transition of a fissure to volcano but retains the architecture of both, which confers it with an inverted, boat hull shape.
Built by repeated eruptions of lava and ash into a tall composite cone, Hekla is a stratovolcano. The bimodal igneous rock composition, from felsic to mafic rocks with little or no intermediate rocks, is indicative of chemical stratification of a magma chamber. It's created as magma differentiates into various melts through processes such as magma mixing, crystal fractionation and crustal rock assimilation (See post Part I here for more details). Since the composition of Hekla's lavas are bimodal and intermediates, the greater viscosity diminishes flow distance, the greater threat being ash.
Hekla means 'short-hooded cloak' in Icelandic and refers to the cloud cover that often drapes over the summit. Its hellish moniker was acquired in the Middle Ages, when without warning in 1104, an intensely violent eruption (Plinian) sent columns of tephra and hot gases high into the atmosphere causing widespread destruction in Iceland and Europe. Foreboding and fiery Hekla appeared on an Icelandic map as early as 1585. The translation of the Latin in the map's text is "Hekla, perpetually condemned to storms and snow, (and) vomits stones under terrible noise."
|Olaus Ortelius' 1585 Map of Iceland and Hekla|
EXPECT THE UNEXPECTED
Resisting a strong urge to continue driving further north into the remote Central Highlands, we reversed our direction and turned toward the South Lowlands and Coastal Plain, the destination of our first night's camp. Briefly, we decided to pull off the F-Road and get one last look at the sleeping giant of Hekla.
In so doing, we were immediately warned by two women in a jeep that we had less than two minutes to move over to the side of the road. What came was a thundering stampede of over 75 beautiful, long-maned Icelandic horses being rounded-up for a cross-country trail ride that operates in the region. With literally only seconds to spare, I took this lucky shot.
|Icelandic Horses in Hekla Country|
Long-lived, muscular and hardy Icelandic horses aren't ponies, just smaller than the common horse. They're
used for sheep herding, racing, showing and trail rides.
ICELANDIC HORSES AND LANGUAGE - ICELANDIC PURITY
By the way, they're not ponies but pure-bred, sure-footed horses with great stamina and endurance that are well-suited for Iceland's rough volcanic terrain. Besides traditional gaits of walk, trot, and canter-gallop, they possess a tölt, known for its explosive acceleration and speed, and a skeið, a fast and smooth "flying pace" for short distances.
They were brought over by Viking Age Scandinavians during the earliest settlement in 874. To prevent genetic dilution (they're the world's purest breed), Icelandic law disallows importation of foreign stock and return of exported animals. It's reminiscent of the protection afforded by the Icelandic government and various affiliated councils that preserve linguistic purity by overseeing the adoption of loanwords from other languages. Both are a vital connection to culture and heritage.
|Quiet and Friendly Majestic Horses of Hekla|
Almost down to the South Coast, we got a great view of glacier Eyjafjallajökull to the east. It's the seventh largest glacier in Iceland with two large glacial tongues on its north slope. It includes a magnificent hiking region of lush, high mountains and glaciers called Þórsmörk (the "Þ" is pronounced "th") or the Valley of Thor. It can also be accessed via mountains pass Fimmvörðuháls from the South Coast.
Recent events have made glacier Eyjafjallajökull very famous for what lies beneath it. Penned E15 by news anchors that couldn't pronounce 'Ey-ya-fyad-la-ou-couth', it covers stratovolcano Eyjafjallajökull. With a summit of 1,651 meters, it has erupted infrequently since the last glacial period, but it's contemporary claim to fame is the massive societal disruption it caused when it did so with little warning in April 2010.
A fissure eruption beneath the glacier led to the development of a new vent on E15's caldera rim. Rapidly generated meltwater flowed in and immediately vaporized. A phreatomagmatic eruption (a magma-water interaction) ensued that elevated its explosive power as gases rapidly expanded and burst a column of volcanic ash (sintered silica-glass particles) high into the upper atmosphere.
This circumstance is by no means unique in Iceland. Countless volcanoes and fissures erupted beneath glacial ice during the Pleistocene that created distinctive volcaniforms and mountains that persist post-glacially on the landscape. In addition, phreatomagmatic eruptions beneath ice caps, in addition to the violent release of gases and ash, also produce sudden catastrophic floods called from the massive release of glacial meltwater.
In the jetstream, E15's tephra (explosively-ejected, pyroclastic volcanic rocks, particles and ash) was distributed across Europe especially Great Britain and Scandinavia. To protect the flying public and prevent aircraft engine damage, over 108,000 flights were cancelled stranding some 7,000,000 passengers over an eight-day period. It was the largest air traffic shutdown since WWII and could happen again at any time.
The event directed global attention to the remote North Atlantic island with everyone discussing hazard forecasting. It has become a sophisticated science involving landscape inflation and ground deformation, satellite imaging of magma, and seismic, GPS, camera and gas emission monitoring.
|Eyjafjallajokull Volcano's Ash Plume on May 10, 2010|
NASA Image courtesy of Jeff Schmaltz, MODIS Rapid Response Team
A GEO-GENETIC LINK TO THE SEA
Eyjafjallajökull means 'ice cap of the island-mountain', penned by early settlers. The name is assumed to refer to nearby Vestmannaeyjar, the Westman Islands archipelago off the South Coast in the East Volcanic Zone. Early Vikings couldn't have understood E15's former proximity to the sea when its south flank once formed a section of the southern coast from which the sea has retreated some 5 km since the end of the Ice Age. It's also true of volcano Katla's south flank some 25 km to the east.
Indeed, the former coastline of both volcanoes is preserved as a long line of tall, ancient eroded sea cliffs that are some 5 to 20 km in-land from the modern South Coast. Driving along the Ring Road, the cliffs are a major attraction for the countless waterfalls that plummet over them, notably Seljalandsfoss and Skógafoss. On a clear day from the coast, you get a great view of the two towering glaciers atop the volcanoes above the cliffs.
FOSSIL SEA CLIFFS OF THE SOUTH COAST
On close inspection, the walls of the sea cliff are constructed of layered flows of lava, tephra and hyaloclastite breccia that formed when lava contacted ice during the Pleistocene or even marine water and then instantly cooled and shattered.
Telltale wave cut notches, sea caves in lowermost sections, pillow basalts (from rapid cooling during subglacial and submarine submersion) and marine terraces substantiate former sea proximity and submersion at or near the end of the last Ice Age some 13,000 years ago, when sea level was perhaps 100 to 150 meters higher than today.
Spherical and tubular-shaped magma forms distinctive pillows about one meter in diameter when extruded under water or ice in a pressurized environment. They are characteristically found under volcanoes as an initial, densely packed deposit in table mountains.
The rim or rind of pillows, which cools more quickly, has a glassy black surface called tachylite. Radial fractures may occur within the mass as the pillow cools and the magma changes volumetrically, reminiscent of columnar jointing. Vesicles may form within the pillow as gas escapes that may subsequently contain minerals such as quartz, calcite or chlorite related to secondary deposition during fluid transport. The in-filled holes may be almond-shaped called amygdules. Combined external pressure and internal gas escape may rupture the pillow into a pillow-breccia mix that leads to pure breccia.
|Cross-Section of Pillows at the Base of Sea Cliff|
The force of the sea attacked the cliff in the Holocene, as glacially-derived rivers and streams spilled over the brink that eroded back the knickpoints (sharp change in channel slope) through Recent times. The cliff's resistant volcanic structure has served to maintain its verticality as it gradually retreated inland.
THE SOUTH COAST
The drive down to the central South Coast from Hekla in the highlands is a dramatic experience of contrasting topography and geology. Bound by the NS-trending West and East Volcanic Zones that are linked by the E-W South Iceland Seismic Zone, the central South Coast transects the lowlands from the base of the Reykjanes peninsula on the west to Hekla (encircled below) on the east.
|West View of South Coast from Dyrhólaey|
Everything in view, the coastline, black sand beach, the sandur and sea cliffs in the distance were shaped and transformed by Pleistocene glacial and Holocene post-glacial processes.
The South Coast region is the source of some of Iceland's largest earthquakes that occur every hundred years or so. Faulting occurs mainly in the two parallel seismic zones - the SISZ and TFZ - and volcanic eruptions are generally preceded by seismic activity.
ERUPTIONS INVOLVING WATER AND ICE
The changing climate, as far back as the Tertiary, has had a profound influence on Iceland's landscape, especially that of the South Coast. As glaciers grew in size during the Pleistocene, subglacial and submarine eruptions became more frequent. Similar to basaltic eruptions, they can occur from a circular vent or linear fissure and form a móberg cone or móberg ridge, respectively.
Water or ice contact produces an eruption that enters a hydromagmatic phase with the generation of profuse tephra. If it continues, the volcano grows large enough to prevent water from entering the vents, the eruption becomes purely effusive with subaerial lava flows over the edifice. The resulting volcaniform is a flat-topped, steep-sided table mountain or tuya ('stapi' in Icelandic). Many were glacially carved into spectacular jagged peaks and deep, broad valleys seen during deglaciated, post-glacial Holocene time.
During the Pleistocene, the Iceland Ice Sheet - part of the Eurasian Ice Sheet, the massive continental glacier system that blanketed northern North America and Eurasia - carved deep troughs into the periphery of Iceland. The weight of glacial ice depressed the landscape, driving its volcanic margins beneath the sea. At the Last Glacial Maximum some 18 to 20,000 years ago, Iceland was completely covered more than double its area in spite of a lower glacioeustatic state with global water bound as ice.
When the Weichselian-age glacier (the final glaciation episode that occurred 120,000 to 10,000 years ago) retreated from South Iceland, the lowlands and coast, both regionally and globally, were inundated by rising seas in the early Holocene, perhaps 100 to 150 meters higher than today. Free from the burden of glacial ice, the depressed Icelandic lithosphere of the coast, lagging behind, began to isostatically rebound in order to maintain equilibrium called glacioisostasy.
Rivers and streams from melting glaciers in the highlands began to emerge and merge and, gathering strength, deliver relentless amounts of volcaniclastic debris of all sizes onto vast sandur plains that developed along the South Coast. Aggradation was assisted in great part by intermittent jökulhlaups (meaning 'running glacier' in Icelandic), massive catastrophic glacial outburst floods from the glaciovolcanic volcanic zones to the north.
The surface of many of the flows have weathered into andisols (fertile volcaniclastic ash soils) that support birch woodlands, shrub heaths and mires and fell. Despite the cool climate and restricted growing season, the water table in the lowlands is high and the site of fairly heavy and frequent precipitation. They support grasses and mosses, hay fields and a variety of food crops of potatoes, turnips, carrots, rhubarb, cabbage, kale, and cauliflower.
WHY ARE ICELAND'S GLACIERS WHERE THEY ARE?
The regional distribution of Iceland's glaciers is an indication of how precipitation arrives with prevailing southerly winds, where the elevated topography exists in the Neovolcanic Zone and where temperatures (below or close to freezing most of the year) sustain glacial snow (where accumulation exceeds ablation and winter precipitation exceeds summer melt).
As the island-blanketing Iceland Ice Sheet progressively diminished in size at the end of the Pleistocene, it formed a number of glaciers in the Holocene identified by ice caps (thick ice mass under 50,000 sq km), ice sheets (over 50,000), outlet glaciers (sub-glacial valleys and channels), piedmont glaciers (outlet glaciers on open lowlands), surge glaciers (short-lived fast-flow) and snow patches (persistent areas of perennial snow and uncompressed granular firn).
BETWEEN THE SEA CLIFFS AND THE COASTLINE
On the afternoon of our first day, having traveled over 180 kilometers from Reykjavik, we reached the lowlands of the South Coast. Continuing our trek on the Ring Road, we began to cross outwash plains Skógasandur and then Sólheimasandur. The latter is southwest of Sólheimajökull, the long-and-slender outwash glacier of parent lacier Eyjafjallajökull.
It has long been studied by glaciologists for its response to changes in climate, both ongoing and in the past. Of interest are its multitude of moraines that confirm repeated advances and retreats as recent as the 19th century as much as two km.
The sandurs are post-glacial features commonly seen in Iceland both within the interior and along the coast. Here, they lie between former sea cliffs and the modern coastline. Subject to the ever-changing volume of glacial meltwater and catastrophic floods induced geothermally and volcanically and from ice-dam and moraine-dam failure, the sandur is a vast expanse of unconsolidated volcanclastic debris and braided rivers and streams on an ever-changing course to the sea - a glacial outwash plain.
InlcudTravelling over a number of bridges that span rivers and streams laden with sediment, we heading for the Katla GeoPark. The UNESCO "unified geographical area" was created for "the protection of the region's natural environment, promotion of local sustainable development and introduction of local culture with a strong emphasis on nature tourism." It covers 9,542 sq km, about 8% of Iceland.
About 2,700 people live within the park and almost two million people visit it annually. It's in the most volcanically active region of Iceland and includes almost every form of volcaniform in addition to immense sandurs, three of Iceland's largest glacial systems, the island's oldest bedrock, tallest mountain and an immense line of fossil sea cliffs with countless waterfalls that spill over them. One corner of the park includes the Iceland mantle plume centered beneath Vatnajökull ice cap.
Click for a larger view.
(Tip: Challenging to pronounce, the suffix of proper names designates a particular landform. Common examples include: -ey for island, -foss for waterfall, -dranger for rock pillar, -fjara for beach, -fjall for mountain, -jökull is glacier, -hellir is cave, -höfði for promontory and -sandur meaning outwash plain.) Here's a complete list.
THE ARCHED-ISLAND WITH A DOOR-HOLE
Having descended to the South Coastal lowlands, the waterfalls and sandurs we visited were in the western portion of the geo-park. Along the coastline, Dyrhólaey is one of Iceland's most photographed landmarks. It's a volcano that erupted from a submarine fissure within the East Volcanic Belt in the late Pleistocene, that contributed the elongate morphology and secondarily erupted after the vent became isolated from the sea. Evidence are sea-quenched hyaloclastites at the base and subaerial caps of lava.
As indicated by the suffix -ey, Dyrhólaey was originally an island before becoming a promontory attached to the mainland in the Holocene by the developing sandur that eventually incorporated it. Of course early Viking settlers could hardly have known that when they titled it, suggesting that the narrow headland was named because it was island-like. Intense erosion and weathering did the rest - glacial and marine - including the semi-circular, 'door-hole' openings at sea level.
Dyrhólaey is the southernmost point in mainland Iceland but briefly lost that distinction to a 1918 Katla eruption-induced jökulhlaup that extended the shoreline about three km to the south. Such is Iceland, dynamic and ever-changing, often catastrophically so. The power of erosion will eventually convert the headland to sea stacks off the coast.
EVOLUTION OF THE SOUTHERN LOWLANDS AND COAST
The views to the west and east from Dyrhólaey reveal much about the geo-evolution of the South Coast and Lowlands. The coastline evolved dramatically during the Holocene via a combination of fluvial, glacial, volcanic and marine processes often working in concert or succession. For example, flat-topped, hyaloclastite mountain Pétursey (center distance) formed in a submarine locale.
It too was likely an island, when it was named by Viking settlers about 1,100 years ago as suggested by its suffix -sey, which means 'island' in Icelandic. Yet today, it's on dry land within sandur Sólheimasandur. The conclusion to be drawn is that once insular and, in the Holocene (most likely), the sandur extended seaward at the rate of ~3 mm per year on average (a simple time-distance calculation).
The view to the east of Dyrhólaey is equally impressive and revealing. Barren, basaltic black sand and pebble beach Reynisfjara borders a large lagoon. It's touted as one of the most beautiful beaches in the world and dangerous due to rogue waves (Tip: Don't turn your back on the ocean near the water).
The coastline forms the strandline (high-water level above shore) at the terminus of Mýrdalssandur. The outwash plain's development and rapid progradation (sedimentary growth) occurred mostly from Katla-originating jökulhlaups and is about 2.2 to 2.5 km south of its year 1660 location. Numerous lava flows are likely buried beneath the coastal sandurs. One example is the Hólmsá lava that is ~7700 years old. Both jökulhlaups and lava flows have significantly and catastrophically changed the topography and hydrology of the outwash plains.
|East View of Mountain Reynisfjall, Sea Stacks Reynisdrangar and Black Sand Beach Reynisfjara from Dyrhólaey|
At 66 m-high, the three rock pillars or sea stacks, Reynisdrangar, off the coast are a famous landmark in Iceland. They persist by virtue of their resistant extrusive and intrusive igneous rocks, although erosion has isolated at sea them from parent mountain Reynisfjall. They are composed of a mix of extrusive and intrusive rocks. Most stacks such as this are feeder-conduits of magma.
|Mountain Reynisfjall and Ever-Popular Sea Cave Hálsanefshellir|
With a blanket of lava, note the extreme flatness of the mountain's topography.
Reynisfjall is genetically similar to Pétursey and Dyrhólaey that emplaced in a submarine locale and were incorporated into the mainland by processes of post-glacial sandur aggradation and isostatic rebound. It's a remarkably flat-topped, steep-sided hyaloclastite mountain (composed of basaltic breccias and tuff) that was constructed of a variety of extrusive and intrusive igneous rock units that indicate it formed in several eruptive phases. It's cap of pahoehoe lava was acquired subaerially from a feeder-dike.
Most of Iceland's table mountains formed under glacial ice during the Pleistocene, although some form under the sea or in deep lakes. And, of course they are still forming today, both on land subglacially and sea. The Surtsey island eruption is a recent example of the latter.
On close inspection of Reynisfjall's exposed south face, an inclined feeder-dike (lower left to upper right) has intruded the contact between contorted columnar basalts of the sill and hyaloclastites that form the mass of the mountain. Above the section (beyond the photo), the dike verticalizes and narrows as it delivered magma to the mountain's pahoehoe cap of lava.
The ever-popular sea cave Hálsanefshellir opens onto beach Reynisfjara at the base of mountain Reynisfjall. It was formed by sea waves crashing into its base. It's most striking feature are the uniform columnar-jointed pillars of basalt that formed as a sill (horizontal intrusion). Emplaced en masse, it gradually cools down to about 800°C from 1200-1300°C. During the process of solidification, it volumetrically contracts into polygonals, typically of five or six sides with columns that many exceed 10 meters in length.
When I first visited the sea cave some 15 years ago, there was only a small dirt parking. Today, there's a large paved lot, visitor center, gift shop, cafeteria and restrooms. It's indicative of the extent tourism is promoted and has grown, now one-third of the island's economy. It helped save Iceland from financial crisis, but airlines are overburdened and prices for goods and serves are rising, not that they were low to begin with. The challenge is how to promote growth and not irreversibly compromise the environment and ecology in the process.
|Sea Cave Hálsanefshellir|
By entering the cave, a unique view of the columns from the underside can be had.
THE HIDDEN FOLK
A widely-held interpretation for the formation of the Reynisdrangar sea stacks, one that is grounded in Icelandic folklore, involves trolls and elves. Social among themselves but unhelpful to humans, they're ugly supernatural beings that live among nature in caves, rocky outcrops and mountain settings in a dark parallel world.
Just off the black sand beach of Reynisfjara, three Huldufólk were caught in morning sunlight, while attempting to drag a ship ashore. Death was certain until the light of dawn struck the creatures and turned them to stone.
|Three Stacks, One Hidden|
BELIEVE IT OR NOT
If you don't think Icelanders take trolls seriously, think again. There are hidden people experts that were consulted before a road was to be excavated through a suspicious lava field and, in one region, before drilling for water. Because many Icelanders believe the human-like elves with pointy ears are everywhere, tiny wooden houses called álfhól are placed in gardens and rocky outcrops for them to live in.
In a land where villages, farms and entire landscapes vanish in the blink of an eye, where massive glacial floods catastrophically pour down from the highlands, where the smell of sulfur from rivers indicates that cauldrons of magma smolder underfoot, where the Northern Lights light up the winter sky and the Midnight Sun illuminates the summer sky, where hot springs and mudpots roil and bubble from the earth, and where glaciers spout skyward on schedule, anything is possible.
|Julia Befriends a Troll (or Vice-Versa)|
Grýla is described as a parasitic beggar who walks around asking parents to give up their disobedient children. I wish I knew about that years ago.
With sunset approaching and only twilight for darkness given Iceland's high summer latitude, we headed to camp at Þakgil for our first night. It's remotely located in the southern Central Highlands some 20 km north of the small South Coast village of Vík í Mýrdal. It's an incredible place, but getting there is half the fun.
The "canyon with a roof" is one of Iceland's "best-kept secrets", of which there are many. It's off the radar on most guide books because of its remoteness and challenge to get to. Having formed as part of a subglacial tuff ridge at the end of the Pleistocene, it was subsequently carved by glacial meltwater at the end of the period. Not to be confused with tufa, a limestone precipitated from groundwater, tuffa is consolidated volcanic ash.
The trek to Pakgill crosses the upper reaches of vast sandur Mýrdalssandur and river Múlakvísl. They're a product of ice cap Mýrdalsjökull, Iceland's fourth largest glacier, and Kötlujökull, its curved outlet to the southeast. The river reaches the North Atlantic east of Vik through the coastal plains of Mýrdalssandur.
|Very Green Section of Upper Mýrdalssandur and Braided-River Múlakvísl|
Standing on one of countless flood terraces of fluvially-delivered volcaniclastic debris, it's a majestic site in the highlands with only the sound of wind and water and no one in sight as far as the eye can see.
A Pakgill Haiku
Our first Icelandic night.
Cold. Windy. Drenched.
Elated. But praying for sun.
|This says it all.|
RETURN TO THE SOUTH COAST
Thor be praised. Our prayers were granted in the morning, when as we broke camp and headed back to the South Coast, the rain abated and the sun miraculously appeared. In fact, we had perfect weather for the remainder of our trip.
Retracing our steps on road Kerlingardalsvegur heading south, we recrossed upper Mýrdalssandur before reaching Höfðabrekkuheiðar. It's part of the same tuff ridge that formed Þakgil subglacially and post-glacially but eroded into a windswept landscape covered by moss and lichen. There's no question that trolls live among the intricate and tortured forms.
Just before hitting the coast, we descended into a serene, glacially-carved valley with a small mountain stream wending its way across the flat, sediment-filled floor. The fertile volcanic soil and coast's high precipitation are perfect for growing hay for animal fodder.
With intermittent sunshine and plentiful rain, the plastic bales of hay seal out oxygen and enhance grass fermentation silage-style. They're color-coded blue to indicate the farmer's contributions to prostate cancer. Yellow bales are also used for various children's cancers and pink for breast cancer.
|Glacial Valley on Road Kerlingardalsvegur just above Vik on the South Coast|
A VOLCANIC MOUNTAIN IN A SEA OF LUPINE
Having reached the lowlands of the coast, east of Vik is Hjörleifshöfði. The table mountains has an interesting historical and geological past. It's named after the brother-in-law of Viking Ingólfur Arnarson, Iceland's first official settler in 874. Hjörleifur met his fate here when he was slain by his slaves and is buried on the summit marked with a stone mound.
The mountain is an inselberg, a stand-alone landform constructed of palagonite, an alteration product from the interaction of water or ice and volcanic glass. It appears as if stranded in the middle of glacial floodplain Mýrdalssandur. How did it get there?
Following deglaciation in the early Holocene, when the low-lying coastal plain was fully emerged, rivers transported volcaniclastic debris on the developing sandur that extended the shoreline to the south and isolated the island-mountain from the sea. The mountain was originally a promontory of the mainland, as indicated by höfði meaning cape.
|A Virtual Sea of Lupine on Mýrdalssandur|
The outwash plain was built via deposition from rivers and streams and countless jökulhlaups generated from ice cap Mýrdalsjökull by glacially-covered volcano Katla. Go there: 63°25'20.85"N, 18°45'14.75"W
RUGGED AND ENDURING BUT HIGHLY VULNERABLE
Hjörleifshöfði is surrounded by another sea, one of purple lupine. It's a visually striking and politically controversial plant in the legume family of peanuts, beans and lentils that's germinating seemingly everywhere in Iceland.
Propelled by climate change, the invasive and tenacious plant out-competes indigenous plants for sunlight. Attempts to plow it under only releases more nitrogen that enriches developing root nodules. It's an example of rugged Iceland's vulnerability in regards to the warming climate. Fortunately, the plant doesn't grow on glaciers, that is until they too succumb to the inevitable.
|Alaskan lupine (Lupinus nootkatensis)|
The circumstance that led to its take-over began a thousand years ago, well before lupine arrived on the island, when the first Vikings cut native birch and other trees for their agrarian and pastoral lifestyles. Over the millennium that followed, severe and widespread wind erosion and soil loss devastated much of the lowlands. In 1954, the solution for soil stabilization and reforestation was to import Alaskan lupine and saplings of birch, pine, spruce and larch from Alaska that thrive in acidic, sandy soil.
It was a challenging undertaking considering the magnitude of Iceland's vast treeless landscape and slow-growth conditions. A seed dispersal program in the seventies to ensure widespread distribution of lupine made things better or worse, depending on your perspective. Lupine remains central to the controversy of making Iceland green or allowing it to become purple.
LAVA FLOWS FROM KATLA AND LAKI FISSURES
Further east, we crossed outwash plain Mýrdalssandur, built by countless jökulhlaups from glacier Mýrdalsjökull. Large portions of it were blanketed by lava flows, two in particular since settlement-times with an incredible history of regional and global devastation. The lavas originated from some of the most volcanically active areas of Iceland from fissure systems in the highlands of the East Volcanic Zone to the northeast of glacier Mýrdalsjökulll towards Vatnajökull.
The first was around 934, shortly after the settlement of Iceland, that possibly lasted nine years. Eldgjá fissures" likely from Katla produced Eldgjárhraun that flowed down glacially-cut valleys to the lowlands and covered a portion of the outwash plain (purple below). The "Fire Lava" was one Iceland's largest post-glacial flows. Had it been 5x10 meters in size, it would have spanned the circumference of the Earth nine times!
The second infamous flow (pink) came with Skaftá Fires (or Skaftáreldar) that erupted from Laki fissures and crater rows (aka Lakagígar) of the Grímsvötn volcanic system, close to glacier Vatnajökull. The violent phreatomagmatic eruption lasted eight months from 1783 to 1784 and produced the Eldhraun flow, the largest since the end of the Ice Age. Reaching the sea, it consisted of 42 billion tons of lava (10X the area of Manhattan) and emitted poisonous clouds of hydrofluoric acid and sulfur dioxide.
The volcanic haze produced Móðuharðindin or "Dusty Hard Times." The "poison from the sky" destroyed ten farms locally and killed over a quarter of the island's population (~9,000) and well over half of the livestock from dental and skeletal fluorosis due to inhalation and ingestion. Crops failed in Europe, droughts occurred in North Africa and India, and one of the longest and coldest winter was recorded in North America. The impact on European climate contributed to an increase in poverty, famine, food prices and bread riots that may have helped trigger the French Revolution in 1789.
In this eastern region of the South Coast, the Ring Road closely parallels the cliffs, indulating in and out. At their lower portions, hyaloclastites document marine weathering along with wave-cut sea caves and beach terraces as compound lava flows cap the summits. Rivers reach the lowlands from a number of south-flowing, 'warm' outlet glaciers that emanate from parent ice cap Vatnajökull.
Even further east on the Ring Road, countless post-Pleistocene age waterfalls cascade from fossil cliffs below Vatnajökull. At intervals, glacially-carved gorges were once filled by outlet glaciers that have either retreated into the highlands. Meltwater in streams from streams and lakes above the cliffs seek the spillways that were created.
It's a spectacular landscape and genetic scenario that's the similar to what we've seen beneath Eyjajallajökull and Mýrdalsjökull to the west. Only here, waters run clear, not sediment-laden with a milky rock flour suspension since Vatnajökull is some distance to the north.
A number of lava flows such as Eldhraun that originated from fissures in the highlands reached the lowlands and coastal sandurs via glacial valleys and notched spillways in the cliff rim. Further east of Dverghamrar (below), one such persistent stream tumbles over steps worn into the lava flow. Joining other tributaries, it will converge into river Skaftá that courses through Brunasandur.
|Glacial River and Terraces along the Ring Road|
The loose material that exists on sandurs both in the highlands and along the coast is the product of Ice Age glaciers. At the base of the base cliffs, a dramatic vegetated apron of talus ends where the expanse of a flat sandur begins that stretches to the sea. Active destructive geological processes are hard at work throughout Iceland.
Notice the solifluction terraces of subtle, parallel steps in the soils and rocks of the unconsolidated slope. Frost-heaving (swelling of soil during freezing caused by an increasing presence of ice as it grows surfaceward) that causes expansive volume changes in uppermost soils and gravity-induced downhill movement regardless of vegetation result in a gradual movement downslope. On a grander scale, the same process produces cirques, an amphitheater or massive bowl-shaped depression on steep glaciated mountain slopes in association with winter-compacted ice, glacial carving and mass wasting.
Wetland vegetation thrives in the damp and water-saturated soils around the streams that course from the base of the cliffs. It includes reeds, rushes, sedges, horsetails, mosses and cottongrass. There are over 606 different species of moss in Iceland.
Iceland currently has six wetlands designated of international importance. Many are located inland and cover almost 10% of the vegetated surfaces of the island. They consist of both andisol (formed from volcanic ash) and histosol (organic peaty) soils, which are uncommon together elsewhere on Earth. Many larger wetlands in Iceland have been drained for cultivational and pastoral purposes, a trend that conservationists and preservationists are worked to cease.
Leaving the cliffs and lowlands of the central-South Coast, we continued our trek northeast to Skaftafell Wilderness, our destination for the second night. But, first we had to cross Skeiðarársandur, the largest outwash plain in the world and actively growing.
With 56 km of coastline and area of 1,300 sq km, Holocene-age Skeiðarársandur formed from the transport of volcaniclastic debris by five or so rivers such as Skeiðará that originates in the highlands. The majority of its meltwater originates from glacier Skeiðarárjökull, one of many south-flowing tongues of Vatnajökull. Countless jökulhlaups have contributed volcaniclastic debris and blocks of ice to the sandur that have been geothermally-spurned by the volcanic systems of Grímsvötn and Öræfajökull that lie beneath Vatnajökull.
|Skeiðarársandur facing South from the Trail to Svartifoss|
From the highlands of the Skaftafell Wilderness, the expanse and immensity of the sandur is evident, even though the photo takes it a small angle of view.
|Mighty Vatnajökull in Southeast Iceland|
In reality, seen from the lagoon of Jökulsárlón, this is the glacial tongue Breiðamerkurjökull of parent ice cap Vatnajökull, whose body-proper looms in the distance some 20 km at the head of the outlet glacier.
REMNANTS OF THE ICELAND ICE SHEET
|Katabatic Wind Simulation|
|Svartifoss from the Banks of River Bæjargil|
|Julia Affectionately Embraces a Downed Hexagonal Column of Basalt|
|Freshwater Spring with Floral Micro-Habitat|
Springs to form in association with dikes and faults by following a path of least resistance.
|Frost-Weathering of the Cliff Face|
|East View of Skaftafellsjökull's Foreland|
|Skaftafellsjökull from the South Flank of the Terminal Moraine|
At 100 meters, it's the highest terminal moraine in Iceland.
At the crest, a glorious view unfolds of the characteristic geomorphic features at the glacier's terminus: a proglacial lake filled with a milky suspension of fine-grained glacial flour and a number of calved icebergs afloat, an ice blue glacial toe filled with kneaded horizons of datable volcanic ash, a steep lateral moraine and a proglacial river heading toward its sandur at the distal end of the foreland. Speculator!
|Glacial Features at the Terminus of Skaftafellsjökull|
Panorama taken from lateral Moraine
|Julia at Skaftafellsandur|
Among the unsorted, unconsolidated glacial till of the outwash plain, Julia delicately balances on a glacially-transported erratic of brecciated hyaloclastite. Note its angular, fragmented clasts of basalt.
A ~700 k-old sediment sequence in the root of Öræfajökull volcano contains fossils primarily of leaves that record climate change on Iceland through the Pleistocene. It's from a deciduous broad-leaf forest that characterized long-gone Tertiary flora. Iceland is composed largely of igneous rocks (25 types) of various types (both volcanic and plutonic), whereas, sedimentary rocks account for about 10% of Iceland's volume. There is no true metamorphic rock, only those altered by geothermal and hydrothermal contact.
After visiting Skaftafellsjökull, we broke camp and headed to Svínafellsjökull, the next outlet glacier in succession to the east. Also south-flowing and part of the Skaftafell Reserve, it formed from the merging of two steep, alpine glaciers and has the appearance of a valley glacier as it flows to its terminus.
|Svínafellsjökull and its Foreland|
Svínafellsjökull is a popular site for guided glacier walks and hiking the lateral moraine on its western flank. Many films and commercials have been filmed there most notably Game of Thrones season 2, where Jon Snow and the Night Watch captured Ygritte.
|Game of Thrones from HBO|
The Skaftafell region is also the site of a long-gone historic farm that played a role in the thirteenth-century Njáls Saga, said to be the most impressive of the medieval Icelandic sagas, prose narratives based on historical events in the 9th through 11th centuries that deal with struggles and conflicts within the early settlers. Basically, it deals with a 50-year blood feud and the consequences of retaliatory vengeance.
|The Snout of SvínafellsjökullI|
Notice the lateral moraine (left) of deposited, unconsolidated bedrock debris.
|Sedge and Cottongrass-Vegetated Skeiðarársandur|
Destroyed by glacial floods and raining ash, farmsteads in the lowlands once stood here. Harsh volcanic conditions have taken their toll on any possible remains. Julia captured this dramatic photo.
|South View of the North Atlantic Coast from the Shore of River Jokulsá|
The Diamond Beach (and massive parking lot) is off to the right. This is a very busy place.
|Stranded Iceberg on Diamond Beach|
After Jökulsárlón, we headed northeast on the Ring Road to our campground destination for the third night. We're now southeast of Vatnajökull with more outlets and their sandurs, but the scenery has begun to undergo a striking change. It's not only the region of the older Tertiary Basalt Formation that formed some 3.3 to 16 my in the Pliocene but the region of dramatic glacial valleys that end in immense fjords that extend below the level of the sea.
The landscape formed before the onset of Pleistocene glaciation but has since succumbed to it with fluvial ravines that were carved into beautifully proportioned U-shaped valleys and alpine-like summits that were intricately sculpted by the movement of glacial ice. Many of the glacial valleys extend below sea level and formed fjords, the most distinctive feature of East Iceland.
OUR THIRD NIGHT
Our camp was located on the shores of fjord Hornafjörður literally in the village of Höfn in southeast Iceland (pronounced 'hup'). The fjord is an estuary (a tidal river mouth), the only navigable one in the country. This is also the region of the Hornafjörður central volcanoes that formed within a Tertiary-age volcanic zone that currently stretches along the southeastern margin of Vatnajökull and northwards, across the eastern fjords.
Many of the volcanoes have been severely eroded by Pliocene and Pleistocene glaciers, and some are still partly covered by Vatnajökull outlets. The eastern landscape includes magnificent outlet glaciers, glacial-carved valleys, moraines and fjords that mark the maximum glacial extent during this time. Here's a sample of what we'll see just north of Höfn tomorrow morning in Post III.
DINNER FROM THE NORWEGIAN SEA
Höfn means 'harbor' in Icelandic, but it might as well be 'Lobster Capital of Iceland.' The coastal village's livelihood centers on fishing and tourism, but hands down, the specialty of the region is lobster or langustines to be more precise. A European term, they look like crayfish with small claws and a large tail (Tip: It's where all the meat is).
Nephrops norvegicus (aka Norway lobster, Scampi or Dublin Bay prawn) thrives on the icy cold seafloor of the Northeast Atlantic and is the most important commercial crustacean not only in Iceland but in Europe. We heard they're more tender and delicious than their larger arthropodal New England relative. So, putting geo-tourism briefly aside, we turned down a tailgate feast of freeze-dried Mountain House lasagna for some of Höfn's finest with ice cold champagne. It didn't disappoint.
|"Now this is roughing it!"|
There was little doubt of the freshness of our sumptuous repast with the fishing vessel that brought in the catch that morning docked literally outside the restaurant.
Following dinner, we turned in with the midnight sun still lighting the evening sky, albeit dimly. Here's our north view of fjord Hornafjörður at high tide and the Tertiary volcanoes along the East Coast from our roof tent at sunset. What a place!
Please join Julia and I for Part III, forthcoming, when we explore the geology of the glaciated fjords of East Iceland, the barren lava fields and sandurs of the Central Highlands, the geothermally and volcanically active Myvatn lakes district, the arctic North Coast and the remote Snæfellsnes peninsula in the northwest.
Here's a small sample of what's to be seen.
I'd like to express my sincere appreciation to the following individuals who were especially helpful in my formulation of this post:
• Guðríður Gyða Eyjólfsdóttir, mycologist with the Icelandic Institute of Natural History, Akureyri Division;
• Ingibjörg Svala Jónsdóttir, Professor of Ecology at University of Iceland for glacial foreland plant identification;
• Ari Trausti Guðmundsson, member of the Icelandic Parliament and geologist, author, lecturer and explorer for a rock specimen identification;
• Wayne Ranney, renown geologist, author, lecturer and guide, for his astute landscape interpretations. Visit him here;
• Gillian R. Foulger, British geologist, author of "Plates, Plumes and Paradigms" and Professor of Physics at Durham University, England for clarification of certain aspects of Iceland geogenetics and mantle dynamics. Visit her here;
• Sigurður Stefnisson, well-known Icelandic photographer for his Eyjafjallajökull photo. Visit him here;
• local Bostonian and Icelander Sonia Didriksson for her valuable geographical assistance and help with everything unpronounceable, especially Icelandic's ten letters that don't appear in the English language.